The AES GCM encryption in mod_auth_openidc uses a static IV and AAD. It is important to fix because this creates a static nonce and since aes-gcm is a stream cipher, this can lead to known cryptographic issues, since the same key is being reused.

From 2.4.9 onwards this has been patched to use dynamic values through usage of cjose AES encryption routines, see:
375407c